ES2251163T3 - SCANNER AND PRINTER OUTPUT SCANNER. - Google Patents

Abstract

A raster output scanner device (36) for a printing apparatus, comprising: a first, a second, a third and a fourth laser source (104) arranged to produce a first, a second, a third and a fourth laser beams (A, B, C, D), respectively; rotating polygonal means having a series of reflective facets (108) arranged to reflect said laser beams on a mobile photoreceptor surface (20) so as to produce scan lines and an optical system to guide the light rays from the first, the second, third and fourth laser sources (104, 204) through the polygonal means towards the photoreceptor surface (20); characterized in that the first and second laser sources are formed by a first double laser diode.

Description

Raster exit scanner and printer.

Electrophotographic marking is a procedure known and commonly used to copy or print documents. He electrophotographic marking is done by exposing a photoreceptor loaded substantially uniformly with a representation of a bright image of a desired document. In response to that light image the photoreceptor is downloaded creating an image latent electrostatics of the desired document on the surface of the photoreceptor Then the toner particles settle on the latent image to form a toner image. That image of Toner is then transferred from the photoreceptor to a substrate of copy, such as a sheet of paper. The image of transferred toner it is then melted into the copy substrate, usually using heat and / or pressure. Then the surface of the photoreceptor of the residual development material and recharges for Prepare for the production of another image.

A procedure to expose the photoreceptor is use a Raster Output Scanner (ROS)). A ROS typically comprises a light source (or sources) laser and a rotating polygon that has a plurality of facets of mirror. The light source radiates a laser beam on the facets of the polygon. The facets reflect the ray on the photoreceptor, producing a point of light. As the polygon rotates the point draw lines, called scan lines, on the photoreceptor. Moving the photoreceptor in a processing direction, to as the point draws scan lines in the fast direction scanning, the surface of the photoreceptor experiences a scan of plot made by the point. During the scan, the laser beam it is modulated with the image information so that it produces a default latent image on the photoreceptor.

The document US-A-5291223 describes a printer in color that includes what are really four ROS scanners in largely independent that simultaneously produce images that correspond to each color separation of an original image. EP-A-0697782 describes a raster output scanner device comprising a first, second, third and fourth laser sources ready to produce a first, a second, a third and a fourth laser beams (A, B, C, D), respectively; polygonal media swivels that have a plurality of reflective facets, arranged to reflect said laser beams on a surface rotating photoreceptor so that lines of production are produced swept; and an optical system to guide the light rays from the first, second, third and fourth light sources through from the polygonal means to the photoreceptor surface.

Although raster output scanners have had a lot of success, when printing at very high speeds they should save significant problems. For example, consider a electrophotographic marking machine that you need to print at 120 pages per minute This requires printing of approximately 22 inches (550 mm) of paper per second and a typical preparation of The image at the same speed. For different reasons (cost, noise, reliability) it is desirable to limit the rotation of the polygon to approximately 20,000 revolutions per minute or even less. For such an application, a ROS of double laser diodes, which produces two scan lines at 600 points per inch at a time, would require a twenty-faceted polygon turning to approximately 19,800 revolutions per minute to meet speed requirements of impression. Unfortunately, said ROS would have problems. First, because of the large number of facets on the polygon, the ROS itself would be very large and should have a focal length of the relatively large scanning optical system. These Features are not compatible with small printers (from desktop). Additionally, said large facet polygon Multiple could be quite expensive.

Therefore, a new scanner device scan output that is capable of printing at very high speeds and that it is compatible with small-sized printers would be beneficial. Even more beneficial could be a new device of raster output scanner that is capable of printing to very high speeds and that is suitable for use in a Small printer and low cost.

According to this invention a device of raster output scanner as described above will characterized in that the first and second laser sources are formed by a first double laser diode, because said means rotating polygonal includes a first rotating polygon, arranged to reflect said first laser beam (A) and said second laser beam (B) on the mobile photoreceptor surface so as to produce a first scan line and a second scan line and a second rotating polygon different from said first polygon rotating arranged to reflect said third laser beam (C) and said fourth laser beam (D) on the mobile photoreceptor surface so that it produces a third scan line and a fourth scan line; because the optical system comprises a first optical system to guide the light rays of the first and the second laser sources through its respective polygon towards the photoreceptor surface, and a second optical system different from said first optical system to guide the light rays of the third and fourth laser sources through their respective polygon towards the photoreceptor surface; because said third scan line is applied to the mobile photoreceptor surface between said first scan line and said second line of swept; and because said second scan line is applied to the photoreceptor surface between said third scan line and said fourth scan line.

An embodiment will be described below. Particular of the present invention with reference to the drawings attachments, in which:

Figure 1 is a schematic illustration of a printing apparatus

Figure 2 is a schematic illustration of a raster output device that has scanners output plot of double laser diodes in tandem.

Whereas the printing technique electrophotographic is well known, the different centrals of processing used in printing machine 4 of electrophotographic illustrated in figure 1 will now be shown in forward only schematically and its operation is will describe only briefly. The reproduction machine incorporates a photoreceptor 20 in the form of a strap that has a Photoconductive surface 21. The photoreceptor is driven by a motor 27 along a path defined by rollers 24, 25 and 26, the direction of the movement being contrary to those of clockwise as shown by arrow 23.

Initially, a part of the photoreceptor 20 passes through a charging center AA in which a generator 28 of corona charges the photoconductive surface 21 to a potential relatively tall and substantially uniform. A source 29 of high voltage power supplies the electrical polarization for the crown generator 28.

Then the loaded part of the surface Photoconductor 21 advances through the BB exhibition center. In  the BB exhibition center, a ROS 36 device produces four lasers, the rays A, B, C and D, which scan the plot by the photoconductive surface. The laser beams expose the photoconductive surface so that the photoconductive surface is discharged to produce a latent electrostatic image of a desired final image. Since the principles of the present invention involve the ROS 36 device, that device is treated with more detail later.

After the latent electrostatic image has been recorded, the latent image is advanced towards a CC central development. There a developer 38 reveals the image latent on the photoconductive surface with toner.

After the latent electrostatic image has been revealed, the photoreceptor 20 continues its rotation and makes advance the image now revealed towards a central DD of transfer. In the transfer center a roller 52 and some guides 56 advance a copy sheet 54 in contact with the revealed image. A crown generator 58 sprinkles ions on the back of the copy sheet so that they attract the image Toner photoreceptor on the sheet. To the extent that photoreceptor continues its advance changes direction in the roller 24. There, the copy sheet with the toner image is separated from the photoreceptor

The copy sheet then advances through a Conveyor belt (not shown) to a fusion central EE. The fusion core EE includes a hot melt roller 64 and a backup roller 66. The copy sheet with your toner image passes through the bite formed between the fusion roller 64 and the backup roller 66 so that the toner image is set in contact with the fusion roller 64. Heat and pressure melt the toner permanently on the copy sheet. After the fusion, the copy sheet advances through a hopper 70 to a Reception tray 72 to be reached by an operator.

After the copy sheet has separated of the photoreceptor, residual toner particles and others wastes that adhere to the photoconductive surface 21 are eliminated in the central cleaning FF. The central cleaning uses a 74 rotating fibrous brush that contacts the photoconductive surface 21. After cleaning, a lamp 75 discharge floods photoconductor surface 21 with light to dissipate any residual electrostatic charge. So he photoreceptor advances to the charging center AA and another one starts print cycle

The electrophotographic printing machine 4 it also includes an electronic subsystem 80 (ESS) that controls the different components and operating subsystems of the machine. In particular, the electronic subsystem 80 which may include a specialized minicomputer, supplies the ROS 36 device with information that has to be marked. It should be understood that the electrophotographic printing machine also includes different power supplies, sensors, mechanical components and user interfaces as required to perform the process of described impression.

Reference is now made to Figure 2, which illustrates a frame output scanner device 36 and section data output of ESS 80 (reference figure 1). He raster output scanner device 36 comprises scanners of tandem frame output. One of the raster output scanners includes a dual laser controller 102 that receives information from video data of the ESS 80. The laser controller 102 activates a double laser diode 104 that emits two laser beams, the A and B rays, which are modulated according to the information in the data of video. The double laser diode 104 comprises two adjoining chips of laser diodes that emit separate laser beams within walking distance. Both laser beams pass through optical system 106 of prebarrido, the type that is usually used of scanners of frame output Double laser beams are reflected from the facets 108 of a polygon 110 that rotates in the 112 direction. reflected laser beams pass through optical system 114 of prebarrido of the type that is usually used in scanners of frame output The laser rays A and B then draw lines of swept through the photoreceptor 20.

The second frame output scanner is essentially identical to the first. The 202 double laser controller receives video data information from the ESS 80. The controller laser then controls a double laser diode 204 that emits two rays laser, the C and D rays, which are also modulated according to the Video data information. The double laser diode 204 is identical to the double laser diode 104.

C and D lasers pass through the system scanning optical 206 and are reflected from facets 208 of a polygon 210 rotating direction 112. The reflected laser beams they then pass through the optical system 214 of prebarrido and draw scan lines through photoreceptor 20.

The laser beams A and B (of the first scanner of frame output) and the C and D laser beams (from the second scanner frame output) draw separate scan lines distance. For example, as shown in Figure 2, the order of the scan lines is A, C, B, D. That is, the scan line produced by laser beam A is next to the scan line produced by the laser beam C. The scan line produced by the laser beam C is between the scan lines produced by the A and B laser beams. The scan line produced by the D laser beam is between the scan lines produced by the C-rays and D. Now, the rotation of the photoreceptor is such that at the moment that the four scan lines referred to above form a image, the photoreceptor 20 has advanced in the direction 23 so that the next scan line produced by the laser beam A be adjacent and properly separated from the scan line previously produced by the laser beam D. As the polygons 110 and 210 continue to turn in direction 112 and that the photoreceptor continues to advance in direction 23, there is a desired electrostatic image on the photoreceptor 20.

The raster scanner device 36 presents advantages in the sense that raster output scanners in Tandem make it possible to use smaller polygons, less facets and slower rotation speeds compared with systems that use only an output scanner of plot of double laser diodes. Although the registration of Multiple laser beams are a problem, different are available techniques to reduce registration problems. For example, by mounting both polygons on the axis of a simple motor, they can reduce or eliminate line speed problems swept. In addition "combining" polygons, that is, well selecting polygons that together result in problems of relatively small record or by matching the facets of polygon 110 that align with the facets of the polygon 210, registration errors can be reduced. Finally, although it is beneficial to use a raster output scanner device of double laser diodes, in tandem, when printed in white and black registration errors between lasers are less important.

Claims (5)

1. An output scanner device (36) of frame for a printing apparatus, comprising: a first, a second, a third and a fourth laser sources (104) arranged to produce a first, a second, third and fourth laser beams (A, B, C, D), respectively; rotating polygonal means that have a series of reflective facets (108) arranged to reflect said laser beams on a mobile photoreceptor surface (20) so that scan lines occur and an optical system to guide light rays from the first, the second, the third and the fourth sources (104, 204) laser through the polygonal means towards the surface photoreceptor (20); characterized in that the first and second laser sources are formed by a first double laser diode (104), because the third and fourth laser source they are formed by a second double laser diode (204), because said rotating polygonal means include a first rotating polygon (110) arranged to reflect said first laser beam (A) and said second laser beam (B) on the mobile photoreceptor surface (20) so as to produce a first scan line and a second scan line and a second rotating polygon (210) different from said first polygon rotating (110) arranged to reflect said third laser beam (C) and said fourth laser beam (D) on the photoreceptor surface mobile (20) so that a third scan line is produced and a fourth scan line; because the optical system comprises a first optical system (106, 114) to guide the light rays of the first and the second laser sources (104) through their respective polygon (110) towards the photoreceptor surface (20) and a second optical system (206, 214) different from said first optical system (106, 114) to guide the light rays of the third and fourth laser sources (204) through their respective polygon (210) towards the photoreceptor surface (20) because said third scan line applies to the mobile photoreceptor surface (20) between said first line of scan and said second scan line, and because said second scan line applies to the photoreceptor surface (20) between said third line of scan and said fourth scan line. 2. A frame output scanner according to claim 1, wherein the first common optical system simple includes a first pre-polygonal optical system (106) between said first double laser source (104) and said first polygon swivel (110) and / or in which the second simple common optical system includes a second pre-polygonal optical system (206) between said double laser source (204) and said second rotating polygon (210). 3. A frame output scanner according to claim 1 or 2, wherein the first common optical system simple includes a first post-polygonal optical system (114) between said first rotating polygon (110) and said surface photoreceptor (20) and in which the second common optical system simple includes a second post-polygonal optical system (214) between said second rotating polygon (210) and said surface photoreceptor (20). 4. A frame output scanner according to any one of the preceding claims, which in addition includes a first and second laser controllers (102, 202), to receive video information, said first controller (102) of laser controls said first double laser source and said second laser controller (202) controls said second source (204) of double laser, so that said first laser beam (A) and said second laser beam (B) are modulated according to said video information by said first laser controller (102) and said third laser beam (C) and said fourth laser beam (D) are modulated according to said video information by said second controller (202) of laser beam. 5. A printing machine comprising: a charged photoreceptor (20) capable of moving in a processing address (23), and a frame output scanner (36) according to any one of the preceding claims arranged to produce from a first to a fourth scan lines on said photoreceptor (20) loaded.